Sound emitting devices of the kind referred to above have been disclosed in the patent literature, but are not commonly available in the market. The devices of this type can be used for many different purposes. One example of such a sound emitting device is a hearing aid. Another example is an earphone for a portable music player. Another example is a headset for a mobile phone.
U.S. Pat. No. 4,133,984 and U.S. Pat. No. 4,834,211 disclose two different examples of sound emitting devices as mentioned in the opening paragraph. Both documents primarily disclose hearing aids, but U.S. Pat. No. 4,133,984 also discloses the use of the sound emitting device as a headphone for an electronic device.
The prior art discloses a number of different inflation mechanisms for inflating the expandable portion of the earpiece. However, the disclosed mechanisms rely on complicated hydraulic or pneumatic systems with integrated check valves, bladders, on/off valves, etc. These mechanisms are therefore rather expensive and complicated to manufacture resulting in high costs. In addition, they are rather difficult for the user to operate since the user needs to manipulate small parts. Other systems rely on external inflating aids which the user is required to carry around.